This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPPthird generation partnership projectCDMcode division multiplexingDLdownlink (Node B towards UE)E-DCHenhanced dedicated channeleNBE-UTRAN Node B (evolved Node B)EPCevolved packet coreE-RGCHE-DCH relative grant channelE-UTRANevolved UTRAN (LTE)HARQhybrid automatic repeat requestHSDPAhigh speed downlink packet accessHS-DSCHhigh speed downlink shared channelHSPAhigh speed packet accessHSUPAhigh speed uplink packet accessLTElong term evolution of UTRAN (E-UTRAN)MACmedium access control (layer 2, L2)MM/MMEmobility management/mobility management entityNode Bbase stationO&Moperations and maintenanceOFDMAorthogonal frequency division multiple accessPDCPpacket data convergence protocolPHYphysical (layer 1, L1)RLCradio link controlRRCradio resource controlRRMradio resource managementSC-FDMAsingle carrier, frequency division multiple accessS-GWserving gatewaySHOsoft handoverSIRsignal-to-interference ratioUEuser equipment, such as a mobile station or mobile terminalULuplink (UE towards Node B)UTRANuniversal terrestrial radio access network
A communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA) has been specified within 3GPP. The DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.7.0 (2009-01), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8)”.
FIG. 2 reproduces FIG. 4-1 of 3GPP TS 36.300, and shows the overall architecture of the E-UTRAN system. The E-UTRAN system includes eNBs, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE (not shown). The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many-to-many relationship between MMEs/S-GW and eNBs.
The eNB hosts the following functions:                functions for RRM: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);        IP header compression and encryption of the user data stream;        selection of a MME at UE attachment;        routing of User Plane data towards the Serving Gateway;        scheduling and transmission of paging messages (originated from the MME);        scheduling and transmission of broadcast information (originated from the MME or O&M); and        a measurement and measurement reporting configuration for mobility and scheduling.        
In Release 8 (Rel-8) of HSPA standardization in 3GPP dual carrier HSDPA was specified in the downlink. In deployments where multiple downlink carriers are available, this multi-carrier operation increases coverage for high bit rates. Rel 8 introduces dual-carrier operation in the downlink on adjacent carriers. This technique doubles the peak rate from 21 Mbps to 42 Mbps without the use of MIMO.
A dual-carrier UE can be scheduled in the primary serving cell as well as in a secondary serving cell over two parallel HS-DSCH transport channels. All non-HSDPA-related channels reside in the primary serving cell, and all physical layer procedures are essentially based on the primary serving cell. Either carrier can be configured to function as the primary serving cell for a particular UE. As a consequence, the dual-carrier feature also facilitates an efficient load balancing between carriers in one sector. As with MIMO, the two transport channels perform HARQ retransmissions, coding and modulation independently. A difference compared to MIMO is that the two transport blocks can be transmitted on their respective carriers using a different number of channelization codes. In terms of complexity, adding a dual-carrier receiver to UEs is roughly comparable to adding a MIMO receiver. Because the two 5 MHz carriers are adjacent, they can be received using a single 10 MHz radio receiver.
In dual carrier HSUPA the UE may be assigned one or two UL carriers for data transmission (if the UE is dual carrier capable). As compared to DL multi-carrier operation, where the UE is required to receive the multi-carrier transmission transmitted by the Node B, in the UL the UE is power limited and thus it needs to share its transmission power among the carriers if it transmits on both carriers simultaneously. Both inner and outer power control loops need to be active on each carrier to maintain synchronization and achieve a desired SIR target.
In future deployments of HSPA networks it is expected that there will be Node Bs that support different releases of the HSPA standard. In other words there may be some Node Bs that support only conventional single carrier HSUPA operation, and some Node Bs that support dual carrier HSUPA operation. In addition, single carrier capable Node Bs may control the same carriers as the dual carrier capable Node Bs.